With the popularity of smart terminals, demands on wireless data service experiences an explosive increase. As predicted, from 2010 to 2015, global mobile data traffic experiences a 24-fold increase, during 10 years from 2010 to 2020, the traffic will see a 500-fold increase. This is a great challenge for the service providing capabilities of the operators. Generally, mobile services of cellular networks are obviously inhomogeneous. According to statistics, about 60% of voice services and 90% of data services are provided indoors. Therefore, for the operators, providing good indoor coverage is an important means to keep customer retention and improve enterprise benefits. However, according to a survey, about 45% of families and 30% of enterprises confront the problem of poor indoor coverage. This is because the current means of providing indoor coverage are mostly based on outdoor macro-cell base stations, and the signals are subject to a high loss when penetrating through the walls.
At present, means of providing indoor coverage include a relay, an indoor DAS, a radiation cable, a small base station and the like. The relay and the radiation cable are gradually replaced by the indoor DAS and the small base station for the reason of complicated assembling. In general, the indoor DAS provides a universal signal coverage for a large-scale indoor environment, but cannot improve capacity for the reason that antenna units are connected to the same base station. Therefore, with an explosive increase of traffic of smart phones and tablet PCs, the indoor DAS would fail to accommodate the requirements. The small base station can solve data capacity problem via deployment of indoor hot spot regions, but cannot cover all regions of a big-scale building. Therefore, in a long time in the future, hybrid deployment of the indoor DAS and the small base station system is very likely to be implemented, so as to effectively provide data capacity and signal coverage.
However, the hybrid deployment of the indoor DAS and the small base station may cause mutual interference. In particular, after 3GPP LTE proposes full-frequency multiplexing to further improve spectrum utilization rate, such mutual interference may be inevitably a critical factor affecting the system performance. At present, to prevent co-channel interference, 3GPP LTE proposes interference prevention method based on interference coordination, and desires to prevent interference by means of orthogonality in the time domain or audio domain. However, these interference coordination manners are all based on small base stations and macro base station, and the small base station and the macro base station have an obvious difference in terms of spatial position. In combination with power control, interference prevention may be achieved. In the small base station and the indoor DAS, the small base station and the indoor DAS substantially overlap in terms of space. In addition, considering the feature of plug-and-play of the small base station, an interference coordination-based method is current developed, for example, ICIC, eICIC and FeICIC, which may not be directly used in interference coordination of the small base station system and the indoor DAS. Therefore, an interference suppression method needs to be redesigned according to the features such as indoor deployment and distributed deployment of the DAS, such that the DAS is capable of normally operating in an environment where interference from the small base station is present.